One known type of disc brake used as a vehicle brake includes a disc rotor which rotates together with the wheel of the vehicle, and a mounting having first and second parallel support arms straddling the outer periphery of the disc rotor. Guide grooves are provided in both support arms facing each other and extend in the direction of the axis of the disc rotor. Pads are disposed between both support arms, each having a first and second convex sections. The first convex section is slidably fitted into the guide groove provided in the first support arm and possesses a cross-section in the axial direction of the disc rotor and in the vertical direction that is generally rectangular. The second convex section is slidably fitted into the guide groove provided in the second support arm and possesses a cross-section in the axial direction of the disc rotor and in the vertical direction that is generally rectangular. The pads suppress the rotation of the disc rotor by contacting the rotary plane of the disc rotor with one side face thereof by being urged in the axial direction of the disc rotor, and are rotated in contact with the disc rotor so that either one side wall among the side wall of the guide groove of the support arm on the outer peripheral side of the disc rotor and the side wall thereof on the inner peripheral side of the disc rotor abuts with one side face, facing to the above-mentioned one side wall, among the side face of the convex section on the outer peripheral side of the disc rotor and the side face thereof on the inner peripheral side of the disc rotor. Pad supports are disposed in the guide grooves of the support arms. Each of the pad supports has a supporting portion positioned between one side wall of the guide groove of the support arm and one side face of the convex section, an urging section urging the convex section toward one side wall and a connecting portion positioned between the bottom of the guide groove of the support arm and a facing plane portion of the convex section facing to the bottom and connecting the supporting portion with the urging section. The urging section is positioned between the other side wall among the side wall of the guide groove of the support arm on the outer peripheral side of the disc rotor and the side wall thereof on the inner peripheral side of the disc rotor and the other side face among the side face of the convex section on the outer peripheral side of the disc rotor and the side face thereof on the inner peripheral side of the disc rotor. A pressing member presses the pads toward the disc rotor.
This disc brake suppresses the rotation of the disc rotor by urging the pads in the axial direction of the disc rotor to contact one side face of the pads against the rotary plane of the disc rotor. Further, one side wall abuts with one side face via the supporting portion of the pad support because the pad turns, in contacting with the disc rotor, so that either one side wall among the side wall of the guide groove of the support arm on the outer peripheral side of the disc rotor and the side wall thereof on the inner peripheral side of the disc rotor abuts with one side face, facing to one side wall, among the side face of the convex section on the outer periphery side of the disc rotor and the side wall thereof on the inner peripheral side of the disc rotor. When one side wall abuts with one side face, frictional force is generated at a part where one side wall contacts with one side face and vibration of the pad during braking is damped, thus suppressing brake squeal.
However, when the pad turns as described above while the pad support is tilted within the guide groove such that the part connecting the supporting portion with the connecting portion approaches one side wall and an edge portion of the supporting portion located on the opposite side from the part connected to the connecting portion approaches one side face for example, the supporting portion of the pad support functions as if it interferes with the abutment of one side wall with one side face, thus generating no frictional force between one side wall and one side face. When no frictional force is generated between one side wall and one side face, the vibration of the pad is not damped during braking action, thus inhibiting the suppression of brake squeal.
Further, when the part connecting the supporting portion and the connecting portion abuts with one side wall and on the fulcrum of this abutting point, the edge portion of the supporting portion abuts against one side face and functions as a spring having a power point at this abutting point, in addition to the supporting portion functioning so as to interfere with the abutment of one side wall with one side face between one side wall and one side face, situations may arise where the vibration of the pad is amplified rather than being suppressed.
In light of the foregoing, a need exists for a disc brake that is capable of reliably and effectively suppressing the vibration of the pads.